Issue with resolving paths with zsh using \0 in variables

[Branden Archer <brarcher@xxxxxxxxxxx>]

This is an issue found when attempting to use paths in zsh where parts of
the path are taken from data on the /sys filesystem. Namely, when cat'ing a
file from the /sys filesystem it may return some data with a \0 at the end.
If that variable is used to form a path the \0 interferes with the path
resolution. Here is an example of this:


root~# echo $ZSH_VERSION
5.3.1
root~# mkdir subdir
root~#
root~# printf "dir\0" > location
root~# touch subdir/myfile
root~# echo "hi" > sub$(cat location)/myfile
zsh: is a directory: subdir
root~# echo "hi" > subdir/myfile


It was found on bash that this did work, so it is believed that this is a
valid use case. Namely, on bash the \0 at the end of the data returned
from $(cat
location) is ignored.

There is a workaround for this, which is to use realpath on the directory
then use the result to access the file:


root~# complete=$(realpath sub$(cat location))
realpath: : No such file or directory
# ^ from stderr
root~# echo "hi" > ${complete}/myfile


However, it would be nicer if that workaround was not necessary.

If you have any questions about this issue, let me know. Thanks!

- Branden